Ouch
In that situation I'd have no choice but to sell and try to downsize. When we moved 5 years ago I extended our mortgage term but kept up the higher payments purely so if the **** hit the fan I knew I could reduce payments back down, and with First Direct there's no limit to the overpayment.
Honestly the properly prices haven’t dropped here. Yet. But we currently throw £2k towards it each month with overpayment included. I’m hoping that worst case scenario we manage the squeeze into that £2k bracket and just write off the monthly overpayment. That way we’d still spend the “same” but end up with no overpayment. Which is a shame but at least our monthly outgoings would stay the same.